1. Field of the Invention
The present invention relates to an information processing apparatus capable of having its main memory expanded while operating.
2. Description of the Related Art
Heretofore, to expand a memory of a system has required three steps: the system is stopped, an additional memory is installed, and the system is restarted. Such techniques are disclosed illustratively in a PC instruction manual, xe2x80x9cHitachi Personal Computer FLORA 1010DI/DM: Your First PC (manual on hardware),xe2x80x9d pp. 107-110 (a Japanese publication; Cited Reference 1). This publication describes the need for expanding a memory of a personal computer with its power cable disconnected. Techniques for connecting a device to a system in operation are disclosed in xe2x80x9cThe Winn L. Rosch Hardware Biblexe2x80x9d by Rosch, Winn L, pp. 347-356, published by Samsung America Incorporated (Cited Reference 2). The Cited Reference 2 discusses PCMCIA specifications for allowing memories to be installed or removed while power is being applied. Other techniques for connecting a device to a system in operation are disclosed in the Jun. 2, 1997 issue of Nikkei Electronics (a Japanese publication), pp. 109-112 (Cited Reference 3). Discussed in the Cited Reference 3 are PCI bus specifications for allowing components to be attached or detached during power application.
Because it has been necessary to stop power to the system when a memory is being added thereto, the expansion of memory resources has conventionally required executing two related processes: stopping the system, and initializing the system. In the case of the operating system (OS) generally used in a workstation/server environment, it has typically taken 30 to 60 minutes to stop and initialize the system, including the steps of stopping and initializing application software.
One way of adding a memory during system operation is by having recourse to a cluster system. The cluster system is constituted by a plurality of information processing apparatuses each performing a specific service. In this system, while one apparatus is being stopped, others function to provide their services continuously. One obvious disadvantage of this system is the need for preparing a plurality of information processing apparatuses.
It is therefore a first object of the present invention to provide a memory managing method for allowing a memory to be added to an information processing apparatus in operation without preparing a plurality of information processing apparatuses.
It is a second object of the invention to provide a memory managing method for reserving a management region of a first memory connected to a processor so that the processor may use an added second memory.
It is a third object of the invention to provide a memory managing method whereby the difference between a predetermined memory size and a currently installed memory size is established as an additional memory size.
In carrying out the invention and according to one aspect thereof, there is provided a memory managing method for use with an information processing apparatus comprising a first memory and a processor for processing information held in the first memory, the information processing apparatus further allowing a second memory to be added thereto while being powered, the memory managing method comprising the steps of: connecting the processor to at least one of the first and the second memories; storing sizes of the first and the second memories connected to the processor; and storing information about whether or not each of the first and the second memories is connected to the processor.
According to another aspect of the invention, there is provided a memory managing method for adding a second memory to an information processing apparatus comprising a first memory, the memory managing method comprising the steps of: establishing a total memory size for the information processing apparatus; calculating a size of an actually installed memory of the information processing apparatus when the information processing apparatus is started; allocating in the first memory a memory management region based on the total memory size; establishing management information about the actually installed memory; calculating as an expandable memory size a difference between the total memory size and the size of the actually installed memory when the second memory is added while the information processing apparatus is operating; and establishing memory management information about the expandable memory size in the first memory.
According to a further aspect of the invention, there is provided an information processing apparatus for allowing a memory to be added thereto while being powered, the information processing apparatus comprising; a first memory; a processor for processing information held in the first memory; and establishing means for establishing a total memory size for the information processing apparatus; wherein the processor calculates a size of an actually installed memory of the information processing apparatus when the information processing apparatus is started; wherein the processor allocates in the first memory a memory management region based on the total memory size; wherein the processor establishes memory management information about the actually installed memory in the first memory; wherein the processor calculates as an expandable memory size a difference between the total memory size and the size of the actually installed memory when the second memory is added while the information processing apparatus is operating; and wherein the processor establishes memory management information about the expandable memory size in the first memory.
The above features of the invention allow a memory to be added to an information processing apparatus while the latter is operating.
Other features, objects and advantages of the invention will become more apparent upon a reading of the following description and appended drawings.